The invention relates to profilometers, and relates in particular to optical profilometers. Profilometers may be used for a variety of applications involving the determination of the depth or contours of a surface. Obtaining information regarding a profile of a surface is important in many areas of manufacturing and research. For example, U.S. Pat. No. 5,565,987 discloses a profilometer system that includes a stylus for closely tracking a surface on a sub-nanometer scale, and U.S. Pat. No. 5,705,741 discloses a profilometer system that includes a constant force mechanism for biasing a stylus arm.
Optical profilometers provide sensitive non-contact profilometry. Certain conventional optical profilometer systems, however, such as those disclosed in Confocal Microscopy with a Refractive Microles-Pinhole Array, by M. Eisner, N. Lindlein, and J. Schwider, OPTICS LETTERS, v. 23, no. 10 (May 1998); and Lithographic Patterning and Confocal Imaging with Zone Plates, D. Gil, R. Menon, D. Carter, and H. Smith, J. VACUUM SCIENCE AND TECHNOLOGY B, 18(6) p. 2881-2885 (November/December 2000) require that a lens array be physically moved to change the focal area during scanning. Such mechanical movement may be time consuming and difficult to achieve in an assembly that is efficient and economical to produce. A variety of optical profilometers have been developed that may avoid moving a lens. For example, U.S. Pat. No. 4,579,454 discloses an optical profilometer in which the position of a focal point within a detector area is determined. U.S. Pat. No. 6,229,617 discloses an optical profilometer system in which light reflected from a surface is interfered with reference laser energy to produce an interference pattern.
There remains a need however, for an optical profilometer that more efficiently and economically determines the spatial profile an area within its field of view.